The invention relates generally to furnace configurations for arranging mechanical and electrical units to carry out heating and cooling processes for electronic component manufacturing, food processing, and medical sterilization. More particularly, the invention relates to a new and improved apparatus for simplifying the processes for electronic component manufacturing, materials processing, and medical applications while reducing energy use and achieving time savings required for such processes.
Conventional furnaces are limited by technical difficulties arising from the use of linear conveyors which are employed to carry objects through the furnace to perform several cycles of heating and cooling through several chambers or zones. Specifically, conventional furnaces used in the electronics industry for processing and soldering Printed Circuit Board (PCB) assemblies are constructed by employing linear conveyors. The object to be heated is placed on the conveyor at an inlet of the furnace and the conveyor then carries the object linearly through a series of heating chambers with pre-set temperatures. Some chambers are equipped with heaters and fans to carry out the pre-heating or intensive heating operations while subsequent chambers are equipped with fans to provide a cooling process of the objects according to process requirements. In this conventional configuration, energy is wasted due to heat losses caused by hot air leaks from the multiple openings in the heat chambers that accommodate the entry and exit of the linear conveyor. Further heat losses are incurred as heated air continuously rises to the top of the heating chambers while the objects pass through the bottom of the heating chambers. Additionally, in a batch process, when the cooling and heating processes are performed in a single chamber, the heating and cooling cycles often prolong the manufacturing processes because the processing cycles require considerable lengths of time for the objects to cool and pre-heat before a next heating cycle may begin. All of these limitations add to the cost and manufacturing complexities when a conventional furnace is employed.
U.S. Pat. No. 5,154,338 discloses an arrangement of heating units with fans in each chamber installed opposite one another above and below the conveyor to constitute a pair along a line and separated by a partial partition so that all the boards can be carried through the chambers from one end (inlet) to another end (outlet). Therefore, at least two operations are required to carry out the tasks of heating profile adjustment, board loading as well as unloading, and quality inspection. The heat generated in each chamber cannot be easily recovered and used again by other chambers unless a special and more costly heat recycle design is implemented to improve the energy recycling. Another limitation of the disclosed arrangement is the limited amount of reduction that can be accomplished in reducing the inner gas consumption by installing the disclosed partitions. The disclosed furnace does not resolve the problem of heat inefficiencies, as the main door of the furnace has to be opened for each loading-unloading cycle. Consequently, the heat applied in the previous batch operation is lost as is the inert gas pumped into the chambers of the furnace. The furnace and the inert gas have to be heated again for each cycle for a period of time.
Another drawback of linear furnaces is that such furnaces are not suitable for applications in offices and laboratories due to the volume occupied by the furnace. Due to the required space, installation of a prior art furnace in a medical laboratory or restaurant for food processing is not feasible even though such furnaces would be quiet convenient and useful for heat treatment.
There is therefore a need for an apparatus that overcomes the limitations of the prior art. There is also a need for an apparatus that is configured for simpler, faster, more energy efficient and economical methods of carrying out heating processes required in varied applications. There is a further need for an apparatus configuration that is smaller, more convenient to operate, and that can be easily adapted for use in different kinds of operational environments for broader applications. There is also a need for an apparatus configured to allow for simplified loading and unloading. There is a further need for an apparatus that minimizes heat losses and reduces inert gas consumption.